Treatment with alcoholic solution to complete coupling of azo dyes in cellulose acetate textile material



Patented June 23, 1953 TREATMENT WITH ALCOHOLIC SOLUTION T COMPLETECOUPLING OF AZO DYES IN TERIAL CELLULOSE ACETATE TEXTILE MA- Victor S.Salvin, Irvington, N. J assignor to Gelanese Corporation of America, NewYork, N. Y., a corporation of Delaware No Drawing. Application December5, 1950, Serial No. 199,363

1 Claim.

This invention relates to th dyeing of textile materials and relatesmore particularly to an improved process for the dyeing by azoic methodsof textile materials made of or containing yarns and filaments having abasis of cellulose acetate Or other organic derivative of cellulose.

An object of this invention is the provision of an improved process forthe dyeing of cellulose acetate or other organic derivative of cellulosetextile materials with azo dyestuffs, and particularly with naphtholbase azo dyestufifs.

Another object of this invention is the provision of an improved azoicdyeing process for the dyeing of cellulose acetate or other organicderivative of cellulose textile materials whereby true, deep shades ofblue, which may be duplicated, may be obtained employing naphthol basedeveloped azo dyestuffs to dye said textile materials.

A further object of this invention is the dyeing of cellulose acetate orother organic derivative of cellulose textile materials with developednaphthol base azo dyestuffs whereby colorations in true blue shades andof excellent resistance to light and crocking may be obtained.

Other objects of this invention will appear from the following detaileddescription.

The dyeing of textile materials with developed naphthol base azodyestuiis has long been employed as a method for the dyeing ofcelluloslc :5:

textile materials such as cotton, or regenerated cellulose prepared bythe viscose process. By this process, a range of heavy shades can beobtained and the resultant dyed cellulose textile materials exhibitoutstanding fastness to washing as well as good resistance to light andto crocking. The application of this method of dyeing to textilematerials having a basis of cellulose acetate or other organicderivative of cellulose has not, however, been as satisfactory as it isin the case of cotton or regenerated cellulose textile materials. Thisis particularly true in the case of dyeings in heavier shades whichemploy components normally yielding blue color ations on cotton orregenerated cellulose materials. Peculiarly enough, azo components whichyield desirable, heavy true blue shades on cotton or regeneratedcellulose materials do not yield the equivalent shade on celluloseacetate or other organic derivative of cellulose textile materials eventhough the same dyeing and coupling technique is employed. Not only hasit been found that the results obtained cannot be duplicated with givencoupling components but it has also been observed that the bluecolorations on cellulose acetate or other organic derivative ofcellulose textile materials are not true blue shades and tend to appearas plum and purple shades. Furthermore, these dyeings do not exhibitparticularly satisfactory wash fastness or light fastness and they arealso quite prone to crocking.

I have now found that cellulose acetate or other organic derivative ofcellulose textile ma terials may be dyed satisfactorily, and in trueshades, with developed naphthol base azo dyestuffs by azo couplingoperation utilizing suitable developers if certain modifications aremade in the usual procedures heretofore employed. In accordance with myprocess, I have found that improved dyeings may be obtained on celluloseacetate or other organic derivative of cellulose textile materials withnaphthol base azo dyestuffs if a condition of low acidity exists duringdiazotization and, more importantly, if the proper degree of penetrationand as complete coupling as possible is achieved during the developmentof the dyeings in said dyeing operations.

I have found that the condition of low acidity during diazotization hasthe highly advantageous effect of reducing the extent to which nitrosonaphthols form during the diazotization reaction. The formation ofnitroso naphthols is quite undesirable during diazotization since thesecompounds tend to produc off-shades and, in tion, appear to beresponsible for a lack of light fastness in the dyed textile material.The low acidity during diazotization is readily achieved by employing anorganic acid of low acidity such as, for example, acetic acid or formicacid in lieu of the excess of mineral acid, such as hydrochloric acid,normally employed during diazoti cation. Preferably, I employ aceticacid to at the desired degree of acidity and in amounts 0.3 to 0.5% byweight on the weight of the aqueous diazotization bath employed.diazotization of the amines employed as coupling components for couplingwith the naphthol base is otherwise carried out in the usual wayemploying sodium nitrite to convert the amine to the diazo compound. Theuse of temperatures of to C. over a period of 20 to 40 minutes issatisfactory in order to effect complete diazotiza tion of the amine.Usually, from about 0.2 to 0.3% by weight of sodium nitrite is employedin the diazotization bath.

To achieve an increased degree of penetration during development,various expedients may be employed. Thus, for example, increased pene-The tration may be attained by increasing the temperature ofdevelopment. Particularly advantageous results are attained whendevelopment is effected at temperatures of '75. to 90 C., or higher, inan alkaline aqueous soap solution. In addition to an increase in thedegree of penetration, an appreciable increase in the speed ofpenetration is also attained. The combined effect of these desirablechanges is a noticeable improvement in shade, particularly in the caseof blue dyeings. Higher temperature also favor a more complete reactionso that any incompletely reacted nitroso naphthols present are held to aminimum. Increased penetration with the production of desirable trueshades, and particularly blue shades, may also be achieved by merelyincreasing the time of development in the aqueous soap solution employedso that not only will the coupling reaction be more com plete but theincreased time permitted will allow the desired, increased degreeofpenetration. to be achieved to produce the true blue shades. desired.Preferably, the aqueous alkaline developing bath is maintained at a pHvof 7.5 to 9.0. q

Highly advantageous results may also be attained by adding agents havinga swelling or solvent action on the cellulose acetate or other organicderivative of cellulose textile material being dyed to the aqueousalkaline soap solution in which development is carried out. Preferably,however, I obtain the increased degree of penetration desired after thedevelopment of the dyestuff on the textile material is. completed in theaqueous alkaline bath, bypassing the textile material carrying thedeveloped dyestufli through. a bath containing such a swelling agent.Examples of suitable swelling agents are ethyl alcohol, the monobutylether of diethylene glycol, diacetone alcohol, triethyl phosphate or themono-butyl ether of. ethylene glycol. In lieu of employing a. treatingbath containing the swelling agent, the textile materialcarrying thedeveloped dyestuif may be exposed to. vapors of a suitable volatileswelling agent, e. g. ethyl alco hol or methyl ethyl ketone.Particularly advantageous results are obtained by the latter methodsince only a very short exposure to said vapors is necessary to producethe desired penetration. Certain dispersing agents also yield valuableresults and in this connection there may be mentioned thenonionicdispersing agents obtained by the condensation of diethanolaminewith long chain fatty acids, such as oleic, lauric, stearic andricinoleic. acid.

Thus, various means may be employed to achieve an increased penetratingaction either during development, or subsequently, and to obtain ascomplete a reaction as possible.

I have also found that thorough scouring of the dyed textile materialafter development has been completed employing an alkaline scouring bathat a temperature of 85 to 90 C. is highly advantageous. Thoroughscouring acts to remove whatever loose particles of nitroso naphtholsthere may be present as well as any other loose dyestufi particles. Theremoval of these loose materials by thorough scouring has been found togive dyeings of noticeably improved light fastness. The high temperatureemployed for said scouring step also acts, in addition, to ensurecomplete coupling of any incompletely coupled components still presentafter the development, and after any one of the above after treatments,whereby the degree of penetration is increased.

in. the. yarns comprising the fabric during spinning operations. Thefabric may also be prenaphtholated by being padded with an aqueousdispersion of the naphthol base and then dried.

' In. order to carry out the coupling reaction, the

naphtholated textile material may then be immersed in a bath containingthe diazotized amine with which the naphthol base is to be coupled.'Ilhe. pre-naphthnlated; textile material may also be dyed with adispersion of the amine coupling component. and the textile materialthus obtained passed into a bath in which diazotization of the aminetakes place. The development of the dyeing, after diazotization, maythen be carried out in any one of the several ways I have describedwhereby improved penetration is attained and with minimum formation ofnitroso naphthols.

In order further to illustrate my invention, but without being limited.thereto, the following examples are given:

Emmple I A fabric woven of cellulose acetate yarn of an acetyl value of54.9,, calculated. as acetic acid, is co-dyed with a dyebath in whichthe dyestuifs present are a mixture of 4-benzoyl-amino-2,5- diethoxyaniline and of the anilide of beta-oxy naphthoic acid in such proportionthat 2% of the former and 2% of the latter is placed upon the fabric.The fabric is then diazotizecl at 20 C. for 30 minutes a diazotizingbath containing 2 grams per liter of sodium nitrite and 5 grams perliter of acetic acid. The diazotized fabric is then rinsed and placed ina developing bath consisting of a soap solution containing on gram perliter of. soap and buffered to a pH of 9. The fabric is maintained insaid bath for 1 hour with the bath at a temperature of 8-5 to C. Thefabric is dyed a violet-blue shade having a 20 hour light fastnesresistance as measured in accordance with the standard A. A. T. C. C.test. Employing a developing bath of the same composition and at atemperature of 65 to 70 C. for 1 hours gives a purple blue shade withonly a 10-hour light fastness resistance.

Example II Example III A cellulose acetate fabric is dyed and diazotizedas described in Example I and is then placed in an aqueous developingbath, buffered to a pH of 9 and containing 0.2% by weight of soap. The

fabric is maintained in the soap solution for /2 hour with the solutionat a temperature of 65 C. The fabric is then removed and placed in a 50%by weight aqueous solution of ethyl alcohol at 25 C. for 1 minute. Thedeveloped fabric is then secured and dried. The cellulose acetate fabricis dyed a true neutral blue shade exhibiting a light fastness resistanceof 40 hours.

Example IV A cellulose acetate fabric is dyed and diazotized asdescribed in Example I and is then placed in a developing bathconsisting of an aqueous 50 by weight solution of ethyl alcohol. Thefabric is maintained in said solution at 25 C. for 3 minutes and is thenremoved and scoured. The fabric is found to be dyed in a true neutralblue shade having a light fastness resistance of 40 hours.

Ewample V A cellulose acetate fabric is dyed and diazotized as describedin Example I and is then exposed for 1 minute to vapors of ethyl alcoholat 80 C. The fabric is then scoured and dried and is found to be dyed atrue neutral blue shade having a light fastness resistance of 40 hours.

While my invention has been more particularly described in connectionwith the use of an anilide of beta-oxy naphthoic acid known as NaphtholAS, equally advantageous results are obtained employing as the naphtholbase, the ortho anisidide of beta-oxy naphthoic acid (Naphthol AS OL)the toluide of beta-oxy naphthoic acid (Naphthol AS/D) and the orthotoluide of hydroxy carbazol (Naphthol AS/LB) as well as other naphtholbases commercially em ployed for the production of naphthol base azodyestuffs. As amino coupling components which may be employed in theproduction of improved dyeings in accordance with my novel process theremay be mentioned 2-methoxy-4-nitro-aniline, ortho nitro aniline,ortho-amino-azo-toluene, paranitro-aniline and toluidine. It is to beunderstood, of course, that not all combinations of naphthol base andamino coupling components yield blue shades. However, my novel processis highly advantageous for increasing the fastness of all of saidnaphthol base azo dyestuffs and, in the case of these combinationsyielding blue dyeings, my novel process is highly advantageous for theproduction of true blue shades of increased resistance to light.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patentis:

In a process for dyeing cellulose acetate textile materials withnaphthol base azo dyestuffs, the steps which comprise applying a mixureof the naphthol base azo dyestuff components to a cellulose acetatetextile material, effecting di azotization of said naphthol base azodyestuff components on said textile material in a diazotizing bathcontaining acetic acid in amounts of 0.3 to 0.5% on the weight of thediazotizing bath, subjecting said cellulose acetate textile materialcarrying the azo dyestuff thereon to the action of a developing bath forsaid azo dyestuif and, after the development of said naphthol base azodyestuff is completed, to the action of a bath containing 20 to 30% byweight of ethyl alcohol at a temperature of 20 to 30 C. for l to 3minutes, whereby more complete coupling of said naphthol base azodyestuff and increased penetration thereof in said cellulose acetatetextile material are attained.

VICTOR S. SALVIN.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 961,241 Knoevenagel June 14, 1910 2,048,786 Ellis July 28,1936 2,048,796 Kirk July 28, 1936 2,090,669 Dreyfus Aug. 24, 19372,218,628 Sowter Oct. 22, 1940 FOREIGN PATENTS Number Country Date470,333 Great Britain Aug. 6, 1937

